> [..]>> Bisecting from 2.6.33.7 to 2.6.33.8 revealed:>> 74a6e0fd8fc216cfa5edcde4bd356a8972cbc74c is the first bad commit>> commit 74a6e0fd8fc216cfa5edcde4bd356a8972cbc74c>> Author: H. Peter Anvin<hpa@linux.intel.com>>> Date: Fri Dec 10 23:57:04 2010 -0500>>>> x86, hotplug: Use mwait to offline a processor, fix the legacy case>>>> upstream ea53069231f9317062910d6e772cca4ce93de8c8>> x86, hotplug: Use mwait to offline a processor, fix the legacy case>> The question would appear to be does mainline beyond this point exhibit> the same symptom?Unfortunately, I could not immediately try to reproduce the situation on a more recent mainline kernel, since the box was freezing while enabling the various services on any kernel >= 2.6.35.

After applying a workaround for this problem which may or may not be related (https://lkml.org/lkml/2011/4/2/33), I was able to test more recent kernels up to 2.6.39-rc1; they all show the same behavior. Interestingly, the system only refuses to power down, if processor frequency scaling was selected. The problem persisted, even if frequency scaling was disabled by selecting userspace or performance scaling_governor before halting the system.